MySqli Database Connection

if(!class_exists('Database')) {
    class Database
    {
        private $db_host = 'localhost';
        private $db_user = 'daso_user1';
        private $db_pass = 'pwd1';
        private $db_name = 'daso_db1';
        private $con = '';
        public $lastQuery = null;

        public function __construct()
        {
            if($_SERVER['HTTP_HOST'] == 'localhost') {
                $this->db_host = 'localhost';
                $this->db_user = 'root';
                $this->db_pass = '';
                $this->db_name = 'db_admin';
            }
        }

    function __destruct()
    {
        // if($this->con) {
        try {
            // if(is_resource($this->con) && get_resource_type($this->con) === 'mysql link') {
            if(isset($this->con->server_info)) {
                /* if server is alive */

 // $page_name = basename($_SERVER['PHP_SELF']);
/*
$actual_link = (empty($_SERVER['HTTPS']) ? 'http' : 'https') 
. "://$_SERVER[HTTP_HOST]$_SERVER[REQUEST_URI]";
*/
// $page_name = $_SERVER['PHP_SELF'];
// $query = "INSERT IGNORE INTO `log_connection_not_closed`(`page_name`) VALUES ('$page_name')";
// $this->con->query($query);

                $this->con->close();
            }
            // else {
            //
            // }
        }
        catch(Exception $e) {
            // echo 'Message: ' .$e->getMessage();
        }
        // }
    }
        public function connect()
        {
            $this->con = mysqli_connect($this->db_host, $this->db_user, $this->db_pass, $this->db_name);
            if(mysqli_connect_errno()) {
                echo "Failed to connect to MySQL: ".mysqli_connect_error();
                die;
            }
            else {
                // $this->con->query("SET NAMES utf8");

                $this->con->set_charset('utf8mb4');
                $this->con->query("SET @@session.time_zone = '+05:30'");

                /*

                $this

                ->con

                ->query("SET sql_mode=(SELECT REPLACE(@@sql_mode,'ONLY_FULL_GROUP_BY',''));");

*/

                

                return $this->con;

            }
        }

    }

}